Lazard's first appearance in Crisis Core is at the beginning of Chapter 2, when Angeal calls Zack to the Briefing Room. As both Zack and Lazard greet each other for the first time, Lazard projects an image onto a screen of the 1st Class SOLDIER, Genesis. He tells Zack that Genesis was sent on a mission to Wutai, but has not returned. As Angeal tells him that they will be leaving immediately, Lazard states he, too, will be going to Wutai. He then is seen again in Wutai when he arrives late and is greeted by Angeal and Zack. Lazard's excuse for being late was that he has not had field experience due to sitting in an office. Nevertheless, Angeal was happy that he came out to Wutai. Lazard explains he had decided to do this because he had guided their forces during the war and wanted to watch them win with his own eyes. Turning towards Zack, Lazard praises him for distracting the enemy and helping Angeal and then tells him he would like to have him for the next mission. Zack then escorts Lazard back to the camp. However, this entire event was in part a cover-up that allowed for Lazard to check in with the members of the Genesis Army stationed in Wutai (the true reason for him being late for his meeting with Angeal and Zack) as well as to evaluate Zack as a risk to their plans.

Lazard appears in Chapter 3 yet again in the beginning, when Zack asks him if there was anything from Angeal, since he had gone missing during the end of the last mission. Unfortunately, Lazard tells him he cannot get a hold of him, even by phone. Zack questions why Lazard had called him to the Briefing Room. He explains to Zack he is to go on a mission to the 1st Class SOLDIER, Genesis's hometown of Banora Village. Lazard also states that Genesis's parents claim he is no longer around, but says he does not trust them because they are his family. He then goes on to telling Zack he had sent people previously, but has had no contact with them since. Lazard turns towards Tseng, and finishes by telling Zack he will be helping him during the mission.

Appearing in Chapter 4, Lazard promotes Zack to a 1st Class SOLDIER. Zack says he does not feel happy at all, but Lazard understands, telling him that a lot has happened within the last few days. After Zack leaves for a few minutes, he makes his way back to Lazard's office. Lazard unfortunately gives Zack the news that he is to assassinate both Genesis and Angeal, and that is also why Sephiroth will be going with him. Unhappy, and angry, Zack asks why he is asking him to do such a thing, but Lazard states that the Shinra army is asking him to. Suddenly, the alarms activate, and Lazard says they have intruders. He then tells Sephiroth he should go to the President's office, and Zack to the entrance.

Lazard disappears after Chapter 4. Many people at Shinra believe he was secretly funding Dr. Hollander with the company's money, as Lazard was doing an unusual amount of research on Hollander, his cover for funding the man's research as well as the Genesis Army.

Later on, Lazard is transformed into an Angeal Copy due to injecting himself with Angeal's cells. Sometime thereafter, he breaks off his alliance with Hollander and Genesis and embarks on a search for Zack. Lazard begins to suffer from the same degradation Genesis and his copies suffer from, and during the four years Zack is imprisoned in Nibelheim, many sightings of Angeal are reported. These sightings are, of course, Lazard.

Zack begins searching for Lazard after escaping from Nibelheim, believing him to be Angeal. Their paths finally cross in Zack's hometown of Gongaga Village when Lazard flies in to help Cloud, who, at this point, is feeling the effects of the Mako poisoning, and Jenova cells. Lazard is easily knocked down by Hollander, who is after Cloud because he possesses Jenova cells, but Zack kills Hollander. Lazard tells Zack he is a clone of Angeal. He had been following Dr. Hollander since Junon after assisting in his escape. However, after becoming a copy, he forgot about his revenge. Instead, his feelings begun to change to the feelings Angeal once had, to help Zack, to save Genesis, but says its much more than that, he wants to save the world.

Soon after the talk, they set off to Genesis's hometown of Banora Village. Once they arrive, they see the Lifestream shooting up into the sky. Soon after Zack goes to investigates it, and Lazard is attacked by Shinra soldiers whilst still looking after Cloud. As Zack comes back after a battle with Genesis, he finds Lazard sitting with Cloud next to a White Banora tree. With his last breath, he tells Zack he fought Shinra troopers whilst looking after Cloud with another copy. Zack realizes the one who fought alongside Lazard was the canine Angeal copy who protected him before, and breaks out in tears as he punches the ground in sadness and frustration.

Lazard's last conversation with Zack.

During the next day, Zack decides to do something memorable for Genesis. He gives around dumbapples for each person - Lazard, Cloud, and Genesis. Soon after Zack and Genesis end their conversation, Genesis passes out, and Lazard and the Angeal copy return to the Lifestream. As the clone disappears, a letter for Zack from Aerith is left behind in its place.

Lazard is another main character, besides Cissnei, to not appear in any of Crisis Core's FMV sequences.

Of all known Angeal Copies, Lazard is the only human copy.

His name and appearance are thought to be recycled from the Square Enix video game, Valkyrie Profile. The name comes from a villain called Lezard Valeth.

Several hints about Lazard being President Shinra's son are hidden throughout Crisis Core. If Zack speaks to a woman outside Aerith's church until Chapter 6, she will give him details about the President's affair with Lazard's mother. Also during Chapter 6, the Shinra guard outside Lazard's office will eventually reveal that Lazard reminds him of the V.P. (Rufus Shinra)

Lazard's surname "Deusericus" was added to the game's English version and was never explicitly stated in the Japanese version. However, in the Japanese version one of the MPs working on the investigation surrounding him mentions that some of his personal and family records may have been falsified. This may include his surname, as Deusericus is meant as a reference to Shinra. It bears the same meaning as the kanji used to write Shinra (roughly "Silken God"), but written in Latin (the other meaning for the second kanji is "Rome", which is used in the Japanese word for Latin).

Lazard's first name is in fact a French surname that in turn was derived from the Eastern European name Lazar, meaning "God help him." The name is also considered to be connected to the New Testament story of Lazarus.